What was with the physics errors?

I noticed two physics errors in the movie:

1. Casey claims that when she brings her arms in while spinning, she increases her moment of inertia. She really decreases it.

2. At a party, Casey says that momentum times velocity is acceleration. It isn't.

In the goofs section of IMDB, it says that these errors may have been deliberately created by the film makers. Why would they create those errors?